Rotation Of Occlusal Plane Research Articles

Dentoalveolar effects of open-bite correction with the dual action vertical intra-arch technique: A finite element analysis.

To evaluate tooth displacement and periodontal stress generated by the dual action vertical intra-arch technique (DAVIT) for open-bite correction using three-dimensional finite element analysis. A three-dimensional model of the maxilla was created by modeling the cortical bone, cancellous bone, periodontal ligament, and teeth from the second molar to the central incisor of a hemiarch. All orthodontic devices were designed using specific software to reproduce their morpho-dimensional characteristics, and their physical properties were determined using Young's modulus and Poisson's coefficient of each material. A linear static simulation was performed to analyze the tooth displacements (mm) and maximum stresses (Mpa) induced in the periodontal ligament by the posterior intrusion and anterior extrusion forces generated by the DAVIT. The first and second molars showed the greatest intrusion, whereas the canines and lateral incisors showed the greatest extrusion displacement. A neutral zone of displacement corresponding to the fulcrum of occlusal plane rotation was observed in the premolar region. Buccal tipping of the molars and lingual tipping of the anterior teeth occurred with intrusion and extrusion, respectively. Posterior intrusion generated compressive stress at the apex of the buccal roots and furcation of the molars, while anterior extrusion generated tensile stress at the apex and apical third of the palatal root surface of the incisors and canines. DAVIT mechanics produced a set of beneficial effects for open-bite correction, including molar intrusion, extrusion and palatal tipping of the anterior teeth, and occlusal plane rotation with posterior teeth uprighting.

Effects of different intrusion patterns during anterior teeth retraction using clear aligners in extraction cases: an iterative finite element analysis.

Overtreatment design of clear aligner treatment (CAT) in extraction cases is currently primarily based on the clinical experience of orthodontists and is not supported by robust evidence on the underlying biomechanics. This study aimed to investigate the biomechanical effects of overtreatment strategies involving different maxillary anterior teeth intrusion patterns during anterior teeth retraction by CAT in extraction cases. A finite element model of the maxillary dentition with the first premolar extracted was constructed. A loading method of clear aligners (CAs) based on the initial state field was proposed. The iterative method was used to simulate the long-term orthodontic tooth movement under the mechanical load exerted by the CAs. Three groups of CAs were utilized for anterior teeth retraction (G0: control group; G1: incisors intrusion group; G2: anterior teeth intrusion group). Tooth displacement and occlusal plane rotation tendency were analyzed. In G0, CAT caused lingual tipping and extrusion of the incisors, distal tipping and extrusion of the canines, mesial tipping, and intrusion of the posterior teeth. In G1, the incisors showed minimal extrusion, whereas the canines showed increased extrusion and distal tipping tendency. G2 showed the smallest degree of posterior occlusal plane angle rotation, while the inclination tendency of the canines and second premolars decreased. 1. In CAT, tooth displacement tendency may change with increased wear time. 2. During anterior teeth retraction, the incisor intrusion pattern can provide effective vertical control for the lateral incisors but has little effect on the central incisors. Anterior teeth intrusion patterns can alleviate the inclination of canines and second premolars, resulting in partial relief of the roller-coaster effect.

Assessing the impact of occlusal plane rotation on facial aesthetics in orthodontic treatment: a machine learning approach

BackgroundAdequate occlusal plane (OP) rotation through orthodontic therapy enables satisfying profile improvements for patients who are disturbed by their maxillomandibular imbalance but reluctant to surgery. The study aims to quantify profile improvements that OP rotation could produce in orthodontic treatment and whether the efficacy differs among skeletal types via machine learning.Materials and methodsCephalometric radiographs of 903 patients were marked and analyzed by trained orthodontists with assistance of Uceph, a commercial software which use artificial intelligence to perform the cephalometrics analysis. Back-propagation artificial neural network (BP-ANN) models were then trained based on collected samples to fit the relationship among maxillomandibular structural indicators, SN-OP and P-A Face Height ratio (FHR), Facial Angle (FA). After corroborating the precision and reliability of the models by T-test and Bland-Altman analysis, simulation strategy and matrix computation were combined to predict the consequent changes of FHR, FA to OP rotation. Linear regression and statistical approaches were then applied for coefficient calculation and differences comparison.ResultsThe regression scores calculating the similarity between predicted and true values reached 0.916 and 0.908 in FHR, FA models respectively, and almost all pairs were in 95% CI of Bland-Altman analysis, confirming the effectiveness of our models. Matrix simulation was used to ascertain the efficacy of OP control in aesthetic improvements. Intriguingly, though FHR change rate appeared to be constant across groups, in FA models, hypodivergent group displayed more sensitive changes to SN-OP than normodivergent, hypodivergent group, and Class III group significantly showed larger changes than Class I and II.ConclusionsRotation of OP could yield differently to facial aesthetic improvements as more efficient in hypodivergent groups vertically and Class III groups sagittally.

Guide Flange Prosthesis: A Case Report

This article introduces the concept of guide flange prosthesis as a rehabilitative solution for patients undergoing hemi-mandibulectomy due to oral squamous cell carcinoma (OSCC). OSCC is a prevalent malignancy, particularly in India, necessitating surgical resection that often leads to functional impairments and aesthetic challenges. Mandibular continuity loss results in issues like mandibular deviation, occlusal plane rotation, and cosmetic disfigurement. The guide flange prosthesis, discussed through a case report of a 45-year-old male post-hemi-mandibulectomy, aims to stabilize the remaining mandibular segment, reduce deviation, and enhance chewing function. The article emphasizes the importance of comprehensive rehabilitation, especially when dental implants may be contra-indicated due to radiotherapy. The case involves the fabrication process of the prosthesis using perforated partial impression trays, irreversible hydrocolloid, and a stainless steel orthodontic wire substructure. The patient's successful adaptation to the guide flange prosthesis, providing stability and improved mastication, highlights its significance in the post-resection phase. The article also discusses the prevalence of oral cancers in India, surgical interventions, and the role of innovative approaches like guide flange prostheses in addressing the challenges of oral cancer reconstruction. Overall, the integration of surgical techniques and prosthetic interventions offers hope for enhanced outcomes in the complex landscape of oral cancer rehabilitation.

Dual-action vertical intraarch technique: A multifocal technique for open bite correction

The dual action vertical intra-arch technique (DAVIT) is an innovative non-compliant multifocal mechanics for open bite correction. It is based on simultaneous posterior intrusion and anterior extrusion, which can occur at similar or different rates according to the patient's needs. This report presents the clinical handling of this innovative mechanics. The occlusal and cephalometric effects of the DAVIT device are shown by the treatment of an open bite Class III malocclusion. Six months after DAVIT placement, the open bite was corrected by increasing the overbite 5.1 mm. Dentoalveolar changes associated with open bite correction with DAVIT included maxillary molar intrusion, maxillary incisor extrusion and palatal tipping, uprighting of maxillary posterior teeth, and maxillary occlusal plane rotation. Maxillary incisor exposure and smile esthetics improved significantly. DAVIT efficiency seems to be associated with its non-compliant multifocal mechanical action, which can be adjusted according to the patient's occlusal and esthetic needs.

Finite element analysis of the biomechanical effect of clear aligners in extraction space closure under different anchorage controls

Clear aligners (CAs) have attracted increasing attention from patients and orthodontists because of their excellent esthetics and comfort. However, treating tooth extraction patients with CAs is difficult because their biomechanical effects are more complicated than those of traditional appliances. This study aimed to analyze the biomechanical effect of CAs in extraction space closure under different anchorage controls, including moderate, direct strong, and indirect strong anchorage. It could provide several new cognitions for anchorage control with CAs through finite element analysis, further directing clinical practice. A 3-dimensional maxillary model was generated by combining cone-beam computed tomography and intraoral scan data. Three-dimensional modeling software was used to construct a standard first premolar extraction model, temporary anchorage devices, and CAs. Subsequently, finite element analysis was performed to simulate space closure under different anchorage controls. Direct strong anchorage was beneficial for reducing the clockwise occlusal plane rotation, whereas indirect anchorage was conducive for anterior teeth inclination control. In the direct strong anchorage group, an increase in the retraction force would require more specific anterior teeth overcorrection to resist the tipping movement, mainly including lingual root control of the central incisor, followed by distal root control of the canine, lingual root control of the lateral incisor, distal root control of the lateral incisor, and distal root control of the central incisor. However, the retraction force could not eliminate the mesial movement of the posterior teeth, possibly causing a reciprocating motion during treatment. In indirect strong groups, when the button was close to the center of the crown, the second premolar presented less mesial and buccal tipping but more intrusion. The 3 anchorage groups showed significantly different biomechanical effects in both the anterior and posterior teeth. Specific overcorrection or compensation forces should be considered when using different anchorage types. The moderate and indirect strong anchorages have a more stable and single-force system and could be reliable models in investigating the precise control of future tooth extraction patients.

Occlusal plane rotation and orthodontic decompensation: influence on the outcome of surgical correction of classIII malocclusion.

The aim of this retrospective multicenter study is to evaluate the influence of surgical manipulation of the upper occlusal plane (UOP) and orthodontic decompensation on the outcome of classIII orthognathic surgery. Incisor inclinations, occlusal plane inclination as well as skeletal and soft tissue changes were assessed in lateral cephalograms of 85classIII patients who had previously undergone orthognathic surgery. Fourteen linear and eight angular measurements were performed on each radiograph at the beginning of treatment (T0), before surgery (T1) and at the end of treatment (T2) using imaging software. After measurement of variables, Mann-Whitney U‑test, repeated-measures analysis of variance (ANOVA) with Bonferroni multiple comparison test, and Spearman's correlation analysis were performed. Astatistically significant improvement was observed in both sagittal skeletal and soft tissue measurements (p < 0.05). Surgical change in UOP was significantly correlated with changes in overbite, upper lip strain and soft tissue B‑point change in the sagittal direction (p < 0.05). Overjet change was significantly correlated with changes in the soft tissue and all sagittal skeletal parameters except for SNA. Changes in the incisor inclinations was significantly correlated with changes in the sagittal skeletal parameters and lower facial height. Significant differences were also observed between the groups with induced clockwise or counterclockwise rotation of the mandible in terms of IMPA (long axis of LI to mandibular plane), overbite, upper lip strain and position of soft tissue B‑point (p < 0.05). Sufficient dental decompensation is crucial for controlling the sagittal as well as the vertical relationship during surgery. Counterclockwise rotation provides an increase in sagittal projection of the mandibular body at the soft tissue B‑point.

Dual-section versus conventional archwire for en-masse retraction of anterior teeth with direct skeletal anchorage: a finite element analysis

BackgroundThe aim of this study is to compare the biomechanical effects of the conventional 0.019 × 0.025-in stainless steel archwire with the dual-section archwire when en-masse retraction is performed with sliding mechanics and skeletal anchorage.MethodsModels of maxillary dentition equipped with the 0.019 × 0.025-in archwire and the dual-section archwire, whose anterior portion is 0.021 × 0.025-in and posterior portion is 0.018 × 0.025-in were constructed. Then, long-term tooth movement during en-masse retraction was simulated using the finite element method. Power arms of 8, 10, 12 and 14 mm length were employed to control anterior torque, and retraction forces of 2 N were applied with a direct skeletal anchorage.ResultsFor achieving bodily movement of the incisors, power arms longer than 14 mm were required for the 0.019 × 0.025-in archwire, while between 8 and 10 mm for the dual-section archwire. The longer the power arms, the greater the counter-clockwise rotation of the occlusal plane was produced. Frictional resistance generated between the archwire and brackets and tubes on the posterior teeth was smaller than 5% of the retraction force of 2 N.ConclusionsThe use of dual-section archwire might bring some biomechanical advantages as it allows to apply retraction force at a considerable lower height, and with a reduced occlusal plane rotation, compared to the conventional archwire. Clinical studies are needed to confirm the present results.

Biomechanical analysis in mandibular advancement and occlusal plane rotation with finite element analysis

We used finite element analysis to assess stress on the cortical bone and plate fixation system, as well as mandibular resistance after sagittal split ramus osteotomy with different mandibular advancements and rotations of the occlusal plane. Three-dimensional mandibular models were obtained, and 6mm and 12mm advancements were planned associated with linear, clockwise, and counter-clockwise rotation of the angle of the occlusal plane. Each model was then fixed with one or two 2.0mm system plates and secured with four monocortical screws. A total of 12 models were built and subjected to a vertical load in the lower central incisor ranging from 50N to 500N in 50N increments. Results showed that the 12mm advancement was associated with higher stress on the bone and plate surface. Additionally, the models fixed with two plates exhibited lower plate stress than those fixed with a single plate. Counter-clockwise rotation of the angle of the mandibular plane in the 6mm advancement caused more plate stress, which did not occur in the 12mm advancement. This analysis has shown that change in the occlusal plane in large mandibular advancements does not act as an additional stress factor. These findings can help to better understand the tensions on bone and plate surfaces in patients who need large mandibular advancements that are associated with a change in the occlusal plane, and will aid better surgical planning.

Comparison of 2 treatment protocols using fixed functional appliances in Class II malocclusion: Treatment results and stability

The objective of this research was to compare the 2 treatment protocols including a functional mandibular advancer (FMA; Forestadent, Pforzheim, Germany) followed by multibracket appliances (MBAs) vs a Forsus device (3M Unitek, Monrovia, Calif) in combination with MBA concerning treatment outcomes and posttreatment stability. This study was conducted using lateral cephalograms of patients who were treated with MBA, which was used either after an FMA or concurrently with a Forsus device, and of patients who had untreated Class II malocclusion (control group). Each group consisted of 19 subjects in cervical stage 2 or cervical stage 3 stages according to the cervical vertebral maturation index. Cephalograms were taken for the treated groups at T1 (pretreatment), T2 (completion of the MBA treatment), and T3 (at least 2years after T2). Significant intergroup differences at the T1-T2 period were observed in favor of the FMA concerning mandibular advancement, intermaxillary relationship, and mandibular elongation. With Forsus treatment, restrained maxillary growth and a slightly improved intermaxillary relationship rebounded after treatment (P<0.05). At the end of treatment, mandibular incisor protrusion and occlusal plane rotation were greater in the Forsus group than in the FMA group (P<0.05), and maxillary incisor retroclination was significant in the Forsus group. During the posttreatment period, although no significant changes were present in the incisors' inclination, relapses of the T1-T2 improvements in overjet and overbite and the recidive of the occlusal plane rotation were significantly higher in the Forsus group. Treatment protocol including an FMA was found to be more effective with mandibular skeletal effects and was more stable with a lesser degree of relapse in overjet and overbite than the Forsus protocol.

O propulsor mandibular pode ser usado com incisivos inferiores vestibularizados?

An excellent alternative to Class II treatment are fixed mandibular propulsion appliances. In general, they are devices that do not cause significant changes in the maxilla or mandible because they promote Class II correction primarily by dental alterations through an increase in the lower incisors inclination, decrease of upper incisors inclination, and occlusal plane rotation. The question is if it is possible to use this type of device, even with the lower dental compensation already present, that is, with the lower incisors vestibularized. The objective of this study is to show through a clinical case the use of mandibular propulsion with this type of malocclusion.

Is alteration of the occlusal plane stable with isolated nasomaxillary fixation of the Le Fort I osteotomy?

The purpose of this work was to evaluate the stability of maxillary position in the setting of occlusal plane rotations in bimaxillary surgery with rigid fixation of the mandible and bilateral nasomaxillary fixation at the Le Fort I level. This was a retrospective assessment of patients undergoing bimaxillary surgery for the correction of dentofacial deformities with occlusal plane alterations. Demographic measures assessed included age, sex, history of craniofacial anomaly, segmental maxillary osteotomy, and maxillary bone grafting. Cephalometric measures assessed included occlusal plane rotation (clockwise (CWR) or counterclockwise (CCWR)), angular measurements of maxillary and mandibular position (SNA, SNB, and ANB), and occlusal plane angle (occlusal plane to corrected Frankfort horizontal); these were assessed preoperatively (T0) and immediately (T1), 6 weeks (T2), and 1year postoperative (T3). Descriptive and bivariate statistics were computed; P≤0.05 was considered significant. Thirty-six patients were included as study subjects (mean age 18.6±1.8 years; 17 (47.2%) female); 27 (75%) had a primary diagnosis of craniofacial anomaly. Eleven patients (30.6%) had segmental maxillary osteotomies; 10 patients (27.8%) had simultaneous maxillary bone grafting. Twelve patients underwent CCWR; 24 patients underwent CWR. No patient required repeat surgery for malocclusion or relapse; there were no malunions or non-unions during follow-up. For CCWR patients, the mean occlusal plane change from preoperative to postoperative was 5.8±2.8°, remaining stable at 1 year postoperative (ΔT3–T1 1.6±1.0°, P>0.05). For CWR patients, the mean occlusal plane rotation was 4.5 ± 2.2°, remaining stable at 1 year postoperative (ΔT3–T1 1.1±0.9°, P>0.05). In patients undergoing bimaxillary surgery for occlusal plane rotation, two-point fixation of the Le Fort I osteotomy resulted in a stable maxillary position at 1 year postoperative.

Occlusal Plane Rotation by Molar Protraction Using Orthodontic Mini-Implant

Occlusal Plane Rotation by Molar Protraction Using Orthodontic Mini-Implant

Cephalometric Evaluation of Dentoskeletal and Soft-tissue Changes with Powerscope Class II Corrector

Objectives: The objective of the study is to assess the skeletal, dental, and soft-tissue effects of PowerScope fixed functional appliance in Class II malocclusion. Materials and Methods: Fifteen late adolescent Class II subjects (CVMI Stages 5 and 6) were treated with fixed mechanotherapy and PowerScope fixed functional appliance. Student t -test was used to compare the cephalometric changes produced before insertion of appliance (T1) and 6 months after the treatment with this appliance (T2). Results: Maxillomandibular relationship improved with significant lengthening of the mandible. There was retroclination of maxillary incisors, proclination of mandibular incisors, extrusion, and sagittal displacement of mandibular molars and clockwise rotation of occlusal plane. Conclusion: PowerScope is effective in correcting Class II malocclusion with a combination of dentoalveolar (primarily) and skeletal changes.

The smile: a challenge in the treatment of class III

The smile poses a challenge in the treatment of class III. Untreated, the class III patient presents excessive maxillary torque and a predominant display of the mandibular incisors, a sign that becomes more visible with age. Functional orthopedics restores the aesthetic appearance of the smile by maxillary protraction (sometimes temporarily because 20% of cases will still need surgery). Depending on the initial severity of the case (-4.5 mm AoBo would be the threshold value), the options are compensation or surgical correction. In both cases, the profile is improved but without normalising the cephalometric values. In recent years, the number of published cases treated by compensations (often using skeletal anchorage) has multiplied with broader indications, particularly for Asian patients in whom Le Fort I surgery gives questionable aesthetic results. Attention must be focused on the occlusal plane rotation which alters the smile by displaying the mandibular incisors. Nevertheless, surgery can handle the most severe cases with a greater degree of improvement. The aim of this article is to determine the cephalometric cut-off values for an acceptable smile in Class III patients. We performed a search on Pubmed using the following keywords: Class III, anterior cross bite, smile, camouflage, orthognathic surgery; then secondarily, using references supplied by the articles found. We then analysed the data. The ortho-surgical protocol associated with extractions of maxillary first premolars appears to be the way to obtain the best results in terms of the smile (versus surgery without extractions and versus orthodontic compensations) because it is, in fact, the only way to restore the normal position and torque of the maxillary incisors, thus increasing their display during smiling.

The stability of occlusal plane rotation during orthognathic surgery

Abstract Background Considered rotation of the occlusal plane and the maxillomandibular complex during orthognathic surgery is an approach that enables optimisation of the functional and aesthetic outcomes of surgical-orthodontic treatment for the correction of a variety of dentofacial deformities. Objectives The objectives of this study are to: (1) retrospectively evaluate the stability of clockwise and anti-clockwise rotation of the occlusal plane during orthognathic surgery, and (2) compare the findings with the stability of orthognathic surgery in which no significant occlusal plane rotation occurs. Aims and methods Data were collected from a sample of 31 adult patients (22 females and nine males) treated by one orthodontist in private practice and at the University of Western Australia from 1992–2008. Patients received a Le Fort I osteotomy and BSSO to reposition the maxilla and mandible, respectively. The patients were separated into three groups defined by no occlusal plane rotation; clockwise occlusal plane rotation; or anti-clockwise occlusal plane rotation. Lateral cephalograms were taken at four time periods during treatment: T1 (pre-surgery), T2 (immediately post-surgery), T3 (six weeks post-surgery), and T4 (longest follow-up). The cephalograms were digitised and analysed using a customised cephalometric analysis (QuickCeph Studio, CA, USA) and landmarks were transferred via cranial base and maxillary superimpositions for each patient from T1 sequentially to T4. Results Clockwise rotation of the occlusal plane was highly stable one year following surgery and showed comparable results with cases treated without occlusal plane rotation. Anti-clockwise rotation of the occlusal plane was less stable and showed significant relapse of the occlusal plane angle towards the pre-surgical value during the post-surgical observation period. Conclusion Clockwise rotation of the occlusal plane during orthognathic surgery appears highly stable. Anti-clockwise occlusal plane rotation during orthognathic surgery appears less stable. Further studies are needed to evaluate the longer-term stability of clockwise and anti-clockwise rotation of the occlusal plane during surgical-orthodontic treatment.

Finite element analysis of different load mode on tooth movement for space closure in patient with bimaxillary protrusion

To investigate the stress distribution on the maxillary anterior teeth retracted with sliding mechanics and micro-implant anchorage using different retraction hook heights and positions. DICOM image data including maxilla and upper teeth were obtained with cone-beam CT. The three-dimensional finite element model was constructed using Mimics software. Brackets and archwire model were constructed using Creo software. The models were instantiated using Pro/Engineer software. Abaqus software was used to simulate the sliding mechanics by loading 2 N force on 0, 2, 4, 6, 8, 10 mm retraction hooks and three different positions, repectively. Rotation of the occlusal plane, the initial displacement and stress distribution of teeth were analyzed. Lingual rotation of maxillary central incisor(0.021°), gingival movement of the maxillary first molar(0.005 mm), and clockwise rotation of the maxillary occlusal plane(0.012°) were observed when the force application point located at the archwire level (0 mm). In contrast, 0.235° labial rotation of the maxillary central incisor, 0.015 mm occlusal movement of the maxillary first molar, and 0.075° anti-clockwise rotation of the maxillary occlusal plane were observed when the force application point located at the higher level(10 mm retraction hook). The more the force application point was located posteriorly at the archwire level, the less lingual rotation of the maxillary central incisor and the more buccal displacement of maxillary first molar was observed. Maxillary anterior tooth rotation and retraction, vertical displacement of posterior segment, and rotation of the occlusal plane could be controlled by adjusting the height and position of the retraction hook in space closure using miniscrew and sliding mechanics.

The short-term skeleto-dental effects of a new spring for the intrusion of maxillary posterior teeth in open bite patients.

BackgroundThe technology surrounding temporary skeletal anchorage devices has improved in leaps and bounds. However, no specific auxiliary exists for the intrusion of molars in conjunction with these devices and currently clinicians are forced to make do with available force delivery materials. A new intrusion auxiliary, the Sydney Intrusion Spring (SIS), was designed to facilitate intrusion without frequent need for reactivation or tissue irritation.MethodsThe subjects consisted of 16 adolescent patients (12 females and 4 males) with an average age of 13.1 years (range 12.2 to 14.3 years). All patients were in the permanent dentition with an anterior open bite of ≥2 mm. Four self-drilling miniscrews were placed into the posterior maxillary buccal alveolar bone. The intrusion appliance consisted of a bonded acrylic appliance and the SIS, activated to produce an initial intrusive force of 500 g. Cone beam computed tomograms were taken after miniscrew placement and at the end of active intrusion. Rendered lateral cephalograms were produced and measurements were taken and compared.ResultsAll study objectives were achieved in 4.91 months (range 2.5 to 7.75 months). The mean molar intrusion was 2.9 ± 0.8 mm (P < .001), resulting in over bite increase of 3.0 ± 1.5 mm (P < .001). The intrusion led to a 2.6° ± 1.3° (P < .001) clockwise occlusal plane rotation and a 1.2° ± 1.3° (P < .01) counter-clockwise rotation of the mandible. Dental measurements showed a significant uprighting and elongation of the incisors. There was no significant extrusion of the lower molars.ConclusionThe SIS is an effective appliance for the intrusion of maxillary posterior teeth, in conjunction with miniscrews.

Cephalometric norms for orthognathic surgery in North Indian population using Nemoceph software

BackgroundCephalometric norms, useful in providing guidance to orthodontist during diagnosis and treatment planning are subjected to variability in morphologic characteristics in different ethnic and racial groups, hence norms established for one population group are not applicable for all. Aims and objectivesTo compare and correlate the established hard tissue cephalometric norms for orthognathic surgery (COGS analysis) given by Legan and Burstone with norms obtained for North Indian population. MethodsPre-treatment digital lateral cephalograms of 100 orthodontically untreated subjects having pleasing profile and normal occlusion in the age range of 18–25 yrs (mean age of 21 ± 2.62 years) were selected. 16 linear and 6 angular hard tissue parameters of COGS analysis were analyzed using nemoceph software for the males and females separately. The data obtained were compared with previously established norms for Orthognathic Surgery using SPSS Version 15.0. ResultsNorth Indian males and females had smaller anterior cranial base length with prognathic maxilla and mandible, protrusive chin with poor chin form, decreased facial height, decreased posterior maxillary height with anticlockwise rotation of mandible, increased anterior and posterior maxillary dental heights, decreased ramal and corpus length, clockwise rotation of occlusal plane, presence of sagittal discrepancy between maxillary and mandibular denture bases in comparison to Caucasian males and females respectively. North Indian females had more proclination of mandibular incisors than Caucasian females. Sexual dimorphism was also evident in the present study with males exhibiting significantly larger cranial base length, greater middle third facial height and posterior maxillary height, counterclockwise rotation of mandibular plane, greater anterior and posterior mandibular dental heights and longer ramal and corpus length in comparison to females. ConclusionNorth Indian population showed significant differences in facial morphology as compared to Caucasians population. Sexual dimorphism was also evident in North Indian populations. Thus the need to develop separate Orthognathic Surgical norms for better treatment planning of North Indian population is justified.

Late Maxillary Protraction in Patients with Unilateral Cleft Lip and Palate: A Retrospective Study

This retrospective study assessed the dentoskeletal effect of late maxillary protraction (LMP; reverse-pull headgear, Class III elastics, and maxillary sutural loosening) in unilateral cleft lip and palate (UCLP) patients versus a control group of untreated UCLP patients. Cephalograms taken at age 13 to 14 years (T1) and 17 to 18 years (T2) were used for this study. The study group comprised 18 patients (10 male and 8 female, mean age at start of LMP therapy = 13.4 [0.45] years). A control groups of 17 patients (8 male and 9 female, mean age = 13.5 [0.44] years) was used for comparison. The repeated-measures analysis of variance showed statistically significant changes across time between groups for the following variables (mean difference [T2-T1] in the study group, 95% confidence interval): SNA (°) (1.95, 0.75 to 3.15), A ⊥ Na Perp (mm) (1.82, 0.86 to 2.77), CoA (mm) (2.92, 1.53 to 4.31), ANB (°) (3.13, 2.02 to 4.24), Wits (mm) (7.82, 5.01 to 10.54), Mx-Md Diff (mm) (0.62, -1.58 to 2.83), Occl P-SN (°) (-3.98, -5.99 to -1.98), overjet (mm) (8.82, 5.90 to 11.74), FMIA (°) (4.05, -0.05 to 8.15), and IMPA (°) (-5.77, -9.74 to -1.80). Late maxillary protraction created a slight open bite (0.66 mm). Trends for overeruption of mandibular incisors and an increase in lower face height (P = .07 for both) were noted in the study group. Late maxillary protraction produced a combination of skeletal changes (protraction of maxilla, improvement in the maxillo-mandibular skeletal relationship) and dental compensations (counterclockwise rotation of occlusal plane, retroclination of mandibular incisors) in patients with UCLP. Late maxillary protraction was also associated with some unwanted tooth movements (open bite tendency, mandibular incisors overeruption).